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12 OSI versus TCP/IP ISO has started recommended OSI by end of 70s TCP IP was already adopted and in use There are very few OSI-based systems running Nearly all the networking softwares and protocols are built on TCP IP model OSI specifications are very complicated to implement as compare to TCP IP. OSI is a 7 layers model and TCP IP, 5. OSI is has a better description of networks and its services. A.Obaid-Wilfried Probst – Rufin Soh INE4481 DISTRIBUTED DATABASES & CLIENT-SERVER ARCHITECTURES

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21 Routing consists of conveying data through the network. All the routing techniques a based on minimal-cost policies: Proportionnal to the network capacity Proportionnal to the traffic load of the line In relation with capacity and load Equal to the length and amount of paquets in the waiting queued on this node THE NETWORK LAYER A.Obaid-Wilfried Probst – Rufin Soh INE4481 DISTRIBUTED DATABASES & CLIENT-SERVER ARCHITECTURES

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24 If J need to compute its new path towards G, it obtains the best cost through H, that is a total amount Of 18 (JH = 12 et HG = 6). Distributed routing techniques: RIP, OSPF,... ROUTING A.Obaid-Wilfried Probst – Rufin Soh INE4481 DISTRIBUTED DATABASES & CLIENT-SERVER ARCHITECTURES New J table gives on the left the distance of the best route and on the rigth column, the next hope to take.